Bacteriology Midterm: Gen Micro

Virus

are considered neither prokaryotes nor eukaryotes because they lack the characteristics of living things, except die ability to replicate.

before

"Pro" means

nucleus

"Karyon" means

Bacteria

These are unicellular organisms that lack a true nucleus, a nuclear membrane and membrane- bound organelles.

Cell envelope

The outermost structure of the bacterial cell.

Cell envelope

It is composed of an outer membrane (Gram-negative bacteria only), cell wall, periplasm (Gram-negative bacteria only) and plasma membrane.

Cell wall

It is also referred to as the peptidoglycan or murein layer.

Cell wall

It is a rigid structure that maintains the shape of the cell.
It is composed of disaccharide-pentapeptide subunits; also made-up of teichoic acid or lipoteichoic acid. Its synthesis and structure has been the primary target of antimicrobial agents.

Cell wall

Function: To prevent bacterial cells from rupturing when the osmotic pressure inside the cell is greater than outside the cell.
It serves as a point of anchorage for flagella.
It determines the staining characteristics of a species.

N-acetyl-D-glucosamine, N-acetyl-D-muramic acid

Gram-positive cell wall consists of glycan chains of alternating __________________and ________________

Teichoic acid

It contributes to the negativity of the cell wall of a gram positive bacteria; it may also bind and regulate the movement of cations into and out of the cell.

Penicillin/Cephalosporins

Antimicrobial drug for gram positive bacteria

Outer membrane

Component of Gram negative bacteria that is composed of proteins, phospholipids and lipopolysaccharide (LPS)

Inner membrane

Component of Gram negative bacteria is the reason for high susceptibility to mechanical breakage.

Periplasmic space

is involved in peptidoglycan synthesis — this space has high concentration of degradative enzymes and transport proteins

Porins

It contributes to the permeability of a gram negative cell wall and allows the passage of small hydrophilic molecules.

phagocytosis

The strong negative charge of the outer membrane is an important factor in evading _____________

Lipid A, Core polysaccharide, Antigenic O

What are the regions of LPS?

Lipopolysaccharides

is vital in evading the host defenses; it contributes to the negative charge of a gram negative bacterial surface (stabilize membrane structure).

2 rings in basal body

Flagellar structure of a gram+

4 rings in basal body

Flagellar structure of a gram-

High

Resistance of gram+ bacteria to physical disruption

Low

Resistance of gram- bacteria to physical disruption

Low

Resistance of gram+ bacteria to Lysozyme disruption

High

Resistance of gram- bacteria to Lysozyme Disruption

High

Sensitivity of gram+ bacteria to penicillin and sulfonamides

Low

Sensitivity of gram+ bacteria to penicillin and sulfonamides

Periplasmic space

It is where β-lactamases are found

Acid fast cell wall

It also contains a waxy layer of glycolipids and fatty acids (hydroxymethoxy acid or mycolic acid) bound to the exterior of the cell wall — a strong hydrophobic structure that affects the permeability of the cell wall.

sterols

Prokaryotes that lack a cell wall contain _______ in their cell membrane.

Mycoplasma and Ureaplasma

Examples of bacteria that has no cell wall

Plasma membrane

It is the deepest layer of the cell envelope; internal matrix of the cell.

Plasma membrane

It is the site of respiration and photosynthesis of bacteria and acts as an osmotic barrier.

Ribosome

Are the sites of protein biosynthesis; give the cytoplasm a granular structure.

70

Ribosomes are ____s in size and dissociates into 2 subunits

Genome

 It consists of a single, circular chromosome.
 It appears as a diffuse nucleoid or chromatin body, which is attached to a mesosome (sac-like structure)

Plasmids

Are extrachromosomal, double-stranded elements of DNA that are associated with virulence.

Plasmids

serve as site for the genes that code for antibiotic resistance and toxin production.

Large plasmid

Responsible for the production of B-lactamase against B- lactam of penicillin and oxacillin

Small plasmid

Resistant to tetracycline and chloramphenicol

Inclusion Bodies

They serve as energy source (food reserve).
Are mainly composed of polysaccharide; and it lessens osmotic pressure.

Ribosome, genome, plasmids, inclusion bodies, endospores

What are the cytoplasmic structures of bacteria?

Babes-Ernest bodies

Inclusion bodies of Corynebacterium

Nocardia and Actinomycetes

It has sulfur granules

Pasteurella and Bordetella

They have bipolar bodies

Asexual spores

Are small, dormant structures that develop inside the bacterial cell as a means of survival against harsh environmental condition.

calcium dipicolinate

Endospores/ Asexual pores is composed of_____________

spore coat

The thick________of endospores is made up of several proteins, and is responsible for chemical resistance - they resist extreme conditions like heat, dryness, and chemical treatment, radiation and dessication.

Sporogenesis/Sporulation

is the process of spore formation.

Germination

The end of the spore's dormant stage

Clostridium tetani

It has a terminal spore

Clostridium botulinum

It has subterminal spore

Bacillus anthracis

It has a central spore

Glycocalyx

Is an outward complex of polysaccharide from the bacterial surface and other cells.
It helps on the attachment of bacteria to surfaces of solid objects or tissue.

Capsule

Is an organized material attached firmly to cell wall.

Slime layer

Unorganized material loosely attached to cell wall.

Capsule

It protects bacteria (virulence factor) from attack by cells of human defense system — resists phagocytosis and desiccation.

Capsule

Prior to serological testing, it has to be removed (by boiling a bacterial suspension) to detect the somatic antigens present underneath them.

Slime layer

It can either inhibit phagocytosis or aid in the adherence to host tissue o9r synthetic implants.

Flagellum

Organ of locomotion

Flagellum

Is an exterior protein filament (flagellin) that rotates and cause bacteria to be motile.
It is important in the survival and the ability of bacteria to cause disease

Gliding motility

is exhibited by cyanobacteria myxobacteria and cytophagas.

Taxis

is the movement of the bacteria toward or away from a particular stimulus.

Atrichous

without flagellum

Monotrichous

Single flagellum on one end

Amphitrichous

Single flagellum on both ends

Lophotrichous

Tuff/ group of flagella on one end or both ends

Peritrichous

spread over the whole surface

Pili

Are hairlike, proteinaceous structures that extend from the cell membrane into the external environment (2 µm in length).

N. gonorrheae

Bacteria without flagellum but with pili

Somatic pili

virulence factor/organ of attachment

Sex pili

Essential for genetic transfer/conjugation process

VABBCCCSSLEPPP

List the Motile Bacteria

KBSP

List the Non-motile/Capsule bacteria

Bacillus and Clostridium

List the bacteria With Spores

Introns

a sequence of base pairs in DNA that interrupts the continuity of genetic information.

Cytoskeleton

the cytoplasmic elements, including the keratin and other microfibrils, that function as a supportive system within a cell, especially an epithelial cell.

0.20-2.0 um

Size of a prokaryotic cell

10-100 um

Size of a eukaryotic cell

archaois

Archaeobacteria is from the word "___________" which means ancient

Methanogens

It contain pseudomurein; obligate anaerobe.

Halobacterium

synthesize ―purple membrane‖ which contains the bacteriorhodopsin; aerobe.

Thermococcus

aka Pyrococcus

Microscopy

Is the most common method used both for the detection and characterization of microorganisms.

Anton van Leeuwenhoek

The first person to observe and describe microorganisms (―animalcules‖) accurately.

Louis Pasteur and Robert Koch

The Great Founders of Microbiology‖

Light Microscope

Visible light is passed through the specimen and then through a series of lenses that reflect the light in a manner that results in magnification of the organisms present in the specimen.
It uses glass tenses to bend and focus light rays and creates magnified images of small objects.  Is determined by numerical aperture and wavelength of light.

parfocal

Ideally microscopes should be __________ — that is the image should remain in focus when objectives are changed

decreasing

The resolution is increased by ______________ the wavelength of light coming from the illuminator.

Bright Field Microscope

Is the most commonly used microscope in a Clinical laboratory.
It forms a dark image against a ―brighter‖ background.
It can distinguish between two dots 0.2µm apart.

Resolution, Magnification, Contrast

3 Properties of Microscope

Resolution

refers to the ability to produce separate images of closely placed objects so that they can be distinguished as two separate entities.

Cedar Wood Oil

Type of oil used in oil immersion field

Base

It holds various parts of microscope, such as the light source, fine and coarse adjustment knobs

C-shaped arm

It holds the microscope, and it connects the ocular lens to the objective lens.

Condenser

focuses a cone of light on the slide

Iris diaphragm

t controls the light that passes through the condenser.

Dark Field Microscope

is used to identify the living, unstained cells and thin bacteria like spirochetes which cannot be visualized by light microscopy.

Phase contrast microscope

This microscope visualizes the unstained living cells by creating difference in contrast between the cells and water. It converts slight differences in refractive index and cell density into easily delectable variations in light intensity.

Phase contrast microscope

consists of an opaque central area with a thin transparent ring which produces a hollow cone of light.